Trump had said earlier Wednesday that he believes that the war on terror will require unprecedented surveillance of America’s Muslims.

“Certain things will be done that we never thought would happen in this country in terms of information and learning about the enemy,” he said in a Yahoo interview. “We’re going to have to do things that were frankly unthinkable a year ago.”

Trump, who rose to the top of the GOP presidential race by focusing on immigration, has repeatedly opposed President Obama’s push to bring 10,000 Syrian refugees into the U.S.

He warned Wednesday of a possible “Trojan horse” in the form of terrorists posing as refugees to get into America.